Place the lamb mince in a bowl and sprinkle with salt. Form into 4 x 150g burger-shaped patties.

Combine the yogurt and mint in a small bowl. Set aside.

To make the pickle whisk vinegar, sugar and salt with 1 cup of water in a small bowl until dissolved.

Add onion and cucumber and leave to sit.

To cook the lamb, rub each patty with a little oil and place on a moderately hot barbecue or frying pan, flipping regularly until cooked all the way through.

To make the sweet potato chips, wash the sweet potatoes and slice as finely as possible using a mandolin or sharp knife. Shallow fry in a fry pan at high heat until crispy. Drain on paper towel and season with salt.

Place a dollop of minted yogurt on each of the bun bases then top with lamb, feta and some of the onion and cucumber pickle.